Heat Traffic Lights for Smarter Energy Use

Energy consumption for heating represents a large share of the total energy demand of buildings. In the 2024 Sustainability Report of our university, for example, roughly 70 % of the campus’s energy use is required for heating, making its reduction a central milestone on the path to climate neutrality. Our research therefore focuses on the development of Heat Traffic Lights (WärmeAmpel) – open source systems that monitor indoor air quality and guide occupants toward energy efficient ventilation behavior. While the university provides a compelling testbed, the same concept can be transferred to any building where heating and ventilation are significant energy consumers.

The heat traffic light combines temperature and CO₂ sensors with a physical traffic light display and an online dashboard that shows real time measurements in a web interface accessible via a QR code. By analyzing the collected data, we can compare the current ventilation strategy with an optimal one that is derived from the limiting air losses and keeping good air quality. We can therefore compare the potential energy savings that result from opening or closing windows at the right moments. In the university setting, the impact is especially pronounced in lecture and seminar rooms, where many users share the same space; the same principle applies to offices, or any other regularly occupied rooms.

The development of the heat traffic light integrate several disciplines: hardware design and integration, data acquisition, statistical analysis, thermal losses modelling, and human centered communication. By providing clear, actionable feedback, the system encourages all users to take part in the building’s climate neutrality effort, taking informed decisions when opening windows or adjusting radiators. In doing so, we aim (a) to raise awareness of heating demand in buildings and (b) to increase user engagement in data driven ventilation decisions, thereby reducing overall heating consumption. A dashboard example is available here.